Amnesia__and_Alzheimer

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					                   Amnesia and Alzheimer’s
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                                    Kim Hyun-woo.
Questions

• What are Amnesia , Alzheimer’s and Dementia?


• Where is Memory?


• What hypothesis can you make from these
  disease? And Design your own experiments to
  prove or disprove it.
Contents
   • What is Amnesia?
   • Classifying Amnesia.
   • H.M. : A Case Study
   • 3 experimental ways (free recall, recognition, cued-
     recall )
   • What is Alzheimer?
   • Memory Span
   • Working Memory
   • Autobiographical Memory
   • Semantic Memory
   • Implicit Memory
   • Location of Memory and the role of hippocampus.
Amnesia ( From Wikipedia )
• Condition in which memory is disturbed
• the inability to imagine the future.
• amnesiacs with damaged hippocampus cannot
  imagine the future.
(Reference) Patients with hippocampal amnesia
   cannot imagine new experiences
           Dementia ( From Wikipedia )
• Etymology
    from Latin de- "apart, away" + mens (genitive mentis) "mind")
•    the progressive decline in cognitive function due to
     damage or disease in the body beyond what might be
     expected from normal aging.
• reversible or irreversible, depending upon the etiology of
  the disease.


• Alzheimer's disease (AD) is the most common form of
  dementia.
• This is incurable, degenerative, and terminal disease.
• Irreversible , not known etiology.
Amnesia ( Category )

• Retrograde (partial or complete) / Anterograde


• Cause


• Location of the brain damage
  particular parts in the brain are implicated in
  memory and amnesia
• Functional deficit
H.M. : A case study
• 27 years old
• For alleviating chronic epileptic seizers
 surgeons severed his hippocampus


• Alleviation of seizers


• But, severe disruption of memory


• Normal on immediate tests , otherwise no
  memory on delayed test.
             Theoretical Accounts of Amnesia(1)
• Hippocampus is involved in mediating memory.
Cons. - maybe surgeons damaged other parts
• Short term memory / Long term memory
Cons.- short memory span doesn’t mean an impaired long term
  memory.
• More recent claim, procedural / declarative memory
According to Cohen & Eichenbaum, amnesiacs can learn the
  solution of the Tower of Hanoi problem. (still controversial)

                            Amnesiacs         Control subjects
           First Day          48.6                 46.7
           Forth Day          34.1                 33.5
      Optimal Performance                31
         Theoretical Accounts of Amnesia(2)
• Implicit and explicit Memory (chapter 7)


• Retrieval Problem
           Test          Control subjects Amnesic Subjects
          Recall              48 %            14 %
         Recognition          94 %             59 %
     Fragmented Word
                              96 %             94 %
       ( Cued-Recall )
          Theoretical Accounts of Amnesia(3)
• The role of context
           Theoretical Accounts of Amnesia(4)
• Amnesiacs can use familiarity on many tasks, this use is
  impaired relative to controls.
• Control subjects can use familiarity and conscious
  recollection.
Alzheimer’s Disease(AD)
• Reported the first case in 1907
• Alzheimer’s Disease is still poorly understood.
• Amyloid plaques , neurofibrillary tangles are
  abnormal structure in the brain of AD patients
• Beta amyloid is toxic to neurons
Alzheimer’s Disease(AD)
Difficulties to understand


-   No symptom
-   Significant cognitive decline with no obvious
    cause
-   As the disease progresses, more areas are
    affected
-   MRI,CT   are useless
-   PET, fMRI are sometime useful
   Amnesia vs Alzheimer’s

                      Amnesia                Alzheimer’s


delayed free recall     X                        X


   recognition          X                        X

procedural learning     O                        X

     priming            O                        X


                                X : impaired

                                O : intact
Alzheimer’s
   • In the early stages of disease, even though
     decreased memory performance,
      the bow shape of serial curve
   • Short memory span
   • Small working memory ( Figure 8.8 )
Alzheimer’s
( Autobiographical memory )




       Bow-shaped serial position curve
Alzheimer’s
( Semantic memory )
• Alzheimer’s patients tend to represent objects in
  term of concrete dimensions such as size instead
  of abstract dimensions
Where is memory?
   • Localized vs Distributed


   • H.M. Case : hippocampus serves the important
     role of memory.


   •    During intentional memory encoding and
       retrieval, universal activation.
   • On evolutionary grounds, Reliance on a central
     memory organ would also be problematic.
Questions
• What are Amnesia , Alzheimer and Dementia?
- Skip
• Where is Memory?
- I agree with the point of view that memory is
    distributed.
• What hypothesis can you make from these
  disease? And Design your own experiments to
  prove or disprove it.


-   Procedural memory is longer than Declarative
    memory.
Q&A

				
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